A new long-necked turtle, Laganemys tenerensis (Pleurodira: Araripemydidae), from the Elrhaz Formation (Aptian–Albian) of Niger

Abstract

An articulated skull and postcranial skeleton of a pelomedusoid turtle, Laganemys tenerensis gen. et sp. nov., is described from the Lower Cretaceous (Aptian–Albian) Elrhaz Formation in Niger. Laganemys has a proportionately long skull, which increases in depth anteriorly, from the occiput to the snout. The thin flat carapace and plastron are covered with fine sulcus-and-ridge texture. The carapace has a deep nuchal embayment anteriorly, a small mesoplastron laterally, and three median fenestrae. The cervical series is nearly as long as the carapace with specialized joints to enhance lateral flexion between cervicals 2 and 3 and cervicals 6 and 7. The relatively long tail is composed of at least 26 vertebrae. Forelimbs and hind limbs have long and relatively straight unguals. Discovered in a fluvial setting, Laganemys would have been an adept long-necked aquatic predator in still waters. A suite of derived features unites Laganemys tenerensis with Araripemys barretoi, a pelomedusoid from northeastern Brazil of similar form, habits and geologic age. These genera provide additional evidence of faunal exchange between South America and Africa in the mid Cretaceous (ca. 110 Mya) prior to the advent of deep waters in the central Atlantic Ocean.